Automated impact device with non-synchronous impacts: a practical solution for modal testing during operation

Ong, Zhi Chao and Lim, Hong Cheet and Brandt, Anders (2018) Automated impact device with non-synchronous impacts: a practical solution for modal testing during operation. Journal of Zhejiang University-SCIENCE A, 19 (6). pp. 452-460. ISSN 1673-565X

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Official URL: https://doi.org/10.1631/jzus.A1700431

Abstract

Previous study has shown that synchronization of phases between impacts and the cyclic load component should be avoided to improve the effectiveness of operational modal testing, i.e. impact-synchronous modal analysis in obtaining a cleaner frequency response function (FRF) estimation with fewer number of averages. However, avoiding the phase synchronization effect is rarely achievable with the current manual impact hammer because of the lack of control of the impact timing. We investigate how to improve FRF estimation in the presence of harmonic disturbances, such as those present in operating rotating machines. An auto impact device is therefore introduced to replace the manual impact hammer. This device ensures that impact intervals can be applied at non-synchronous instances with respect to the harmonic disturbance. We demonstrate that this new device is a viable option for operational modal testing. It allows significant improvement in FRF estimation and shows good correlation of modal extraction data with benchmark experimental modal analysis results.

Item Type: Article
Uncontrolled Keywords: Auto impact device; Frequency response function (FRF); Impact-synchronous time averaging; Manual impact hammer; Phase synchronization; TH16
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Faculty of Engineering
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 24 Apr 2019 07:15
Last Modified: 24 Apr 2019 07:15
URI: http://eprints.um.edu.my/id/eprint/21062

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